The Grey Seal (Halichoerus grypus) is a large carnivorous mammal living in the coastal waters of the North Atlantic ocean. Their Latin name Halichoerus grypus translates as “hook nosed sea pig”. Over half of the global population is to be found in British waters.
It is the largest of the British seals and can be distinguished from the common seal by its flat or straight face profile (the common seal having a somewhat snub nose). The largest proportion of grey seals are in Scottish island colonies such as North Rona, other significant colonies can be found on the Farne Islands and on Ramsey Island. Ramsey island, cared for by the RSPB, is situated in the Irish sea just off the west Wales coast; this is where I visited recently.
Male grey seals grow up to 2.5m long, weighing up to 300kg; the females are smaller than the males and are often lighter coloured than the males. A female seal will typically mate in the autumn. The young embryo will only develop briefly before entering a period of suspended development (delayed implantation), typically 3 months. This allows the female time to recover from a previous pregnancy and ensures the annual timing of births. After this pause, pregnancy will continue as normal for approximately 8.5 months, with a young pup being born the following autumn.
Pups are born with a thick white furry coat, called lanugo. Some are born on isolated rocky beaches and others deep within coastal caves. In their first few days they appear wrinkled & yellowy but soon fill out to fit their white coat. They feed typically 4 times per day on their mothers extremely rich milk (58% fat); allowing them to gain weight at a prodigious rate of almost 2kg per day. After about 3 weeks of eating & sleeping the young pup will moult its white fur and gain a more adult appearance. This is also a typical time for weaning. Before leaving their pups the mothers encourage them into the water & ‘play’ with them but then they must abandon the pups, mate & gain condition ready for next year’s birth.
The young pups will now start to explore their marine environment, learning to hunt & eat the variety of fish that will sustain them throughout their adult lives; this includes species such as sand eels, herring and skate. Seals can dive under water for 25 to 30 minutes. They have a specialised circulatory system that stores oxygen rich blood near to the muscles, whilst shutting down their pulse rate to a mere 5 – 10 beats per minute versus the 70 – 80 bpm it more normally is at the surface. The seals will now spend much of the coming months out at sea only occasionally coming to land for a few days rest.
The young females will not reach sexual maturity until about 5 years of age, however they will often live until 40 or so years of age. The bulls usually only live into their late twenties.
Grey Seals were hunted to dangerously low numbers at the end of the 19th century, they provided oil for fuel and skins for clothing. In 1914 the British government passed a protection act for the grey seals; this was extended in 1932 and updated in 1970. The protection has allowed the species to recover but there are still threats:
- Calls for seal culls from fishermen, including the Scottish salmon farming industry
- Oiling from tankers & spills
- general ecosystem degradation
Responsible viewing: Seals are beautiful & fascinating creatures but human disturbance can be a problem to them. Whether on land or sea you should not approach seals within a distance that disturbs them. Keep an eye on their reactions, if they become nervous or move away, then you are too close. Young seals pups make pitiful cries that sound like a plea for help, this is normal, do not attempt to move them; if you are really concerned, contact the local wildlife expert / charity.
If you’d like to view a brief video of a young seal pup then please do follow either of the links below: